vol. 96 | iTHES

Vol. 96, September 28th, 2015


  • Upcoming Events
  • Event report
  • Person of the week

Person of the week

Jirong Mao


Matter Mixing in Core-collapse Supernova Ejecta

From the Office

The office of iTHES assistant, Ms.Chikako Oota is situated at the second floor of the main research building, room # 246. The extension number is 3261. She will be at the office from 10 a.m. to 16 p.m.

Upcoming Events

RIKEN Nishina Center - RIKEN iTHES Joint Seminar

Prof. Bikash Sinha (Variable Energy Cyclotron Centre, India)
Date: Oct. 6 (Tues.) 2015, 15:00-16:30
Place: Nishina Hall
Over the years India’s scientific enterprise is inevitably moving towards a global perspective. Mega Science, almost by definition is multi disciplinary and multi institutional and of course global. In India scientific institutions from small and modest enterprises have gone on to build mega science facilities in India as well as participate in mega science facilities across the world. The evolution of this adventurous journey from the early sixties to now will be traced touching upon the speaker’s personal involvement.

The 6th iTHES Academic-Industrial Innovation Lecture

"Recent advances in computaBonal drug discovery research"
Hironori Kokubo (Takeda Pharmaceutical Company)
Date: Oct. 22(Thurs.) 15:00-17:00
Place: Big conference room (2nd floor of the main cafeteria)

iTHES Colloquium in November 2015

Date: Nov.10 (Tues) 15:00-16:30
Place: big conference room (2nd floor of the main cafeteria)
Speaker: Kazuyuki Aihara (Univ. Tokyo)
Title: TBA

Osaka CTSR - Kavli IPMU - RIKEN iTHES International workshop
"Nambu and science frontier"

Date: 17th November (Tue), 2015
Venue: H701 lecture room, Dept. of Physics, Osaka university
Time: 9:30 - 17:30

Invited speakers
Kenji Fukushima (U. Tokyo)
Koji Hashimoto (Osaka U)
Simeon Hellerman (Kavli IPMU)
Noriyoshi Ishii (Osaka U)
Kota Masuda (RIKEN iTHES)
Yu Nakayama (Kavli IPMU / Caltech)
Toshifumi Noumi (Hong Kong U. of Science and Technology / RIKEN iTHES)
Kin-ya Oda (Osaka U)
Noriaki Ogawa (RIKEN iTHES)
Haruki Watanabe (MIT)
Tamiaki Yoneya (U. Tokyo, Open Univ. of Japan)

Koji Hashimoto, Kentaro Nagamine (Osaka CTSR)
Tetsuo Hatsuda, Tsukasa Tada, Masato Taki (RIKEN iTHES)
Hitoshi Murayama (Kavli IPMU)

Purpose of the Workshop:
In July 2015, we as the physics community were greatly saddened by the news that Prof. Yoichiro Nambu had passed away. He proposed many of the fundamental concepts that underlie our current understanding in theoretical sciences. On this occasion, we’d like to discuss the relevance of Nambu’s concepts and how they will be developed in many areas of science, and promote interdisciplinary collaborations among theoretical sciences. The joint workshop of Osaka CTSR- RIKEN iTHES - Kavli IPMU is a successive series following the symposium held at Kavli IPMU last year.
The topic of the workshop includes:
- Nambu-Goto action for strings, membranes and higher dim. objects
- Nambu-Goldstone theorem and its extensions
- Nambu-Jona-Lasinio model and its generalizations
- Nambu-Bethe-Salpeter equation and nuclear/hadron physics
- Nambu bracket for quantizing membrane and M-theory
- Higgs inflation
- QCD chiral phase transition
- Symmetry breaking in physical biology

Sponsored by
- Core for Theoretical Science Research (CTSR) , Osaka Univ.
- Interdisciplinary Theoretical Science (iTHES) Research Group, RIKEN
- Kavli IPMU, The Univ. of Tokyo

Fundamental Physics Using Atoms 2015
- Towards better understanding of our matter universe -

Nov. 30 (Mon.) -- Dec. 1 (Tue.), 2015
Oral sessions: RIKEN Wako, Okochi Hall (C32)
Poster sessions: Welfare and Conference Bldg. 2F (C61)

Recently much effort has been directed to investigation of the fundamental physics which exploits remarkable developments in atomic physics and/or quantum optics techniques. Examples include (A) test of the time reversal invariance by observing permanent electric dipole moments of atoms or molecules, (B) neutrino mass spectroscopy using atoms, (C) measurement of fine structure constant's time dependence with precession atomic clock etc. This conference aims to bring together recent research results, to discuss future prospects, and to expand research network, making this field more active and productive.

Event report

The topic of 12th iTHES Colloquium was, atypical for the occasion, something directly connected to everyday life: weather forecast.
Dr. Takemasa Miyoshi, the team leader of Data Assimilation Research Team at RIKEN Advanced Institute for Computational Science, also a new member of ithes-mcc team, gave his lecture entitled "Numerical Weather Prediction: Chaos, Predictability and Data Assimilation" on Tuesday 15th. Dr. Miyoashi used to work for the Japanese Meteorological Agency, so he certainly qualifies to talk on the subject. He employs the technique called data assimilation whose core idea stems from statistical mechanics. His lecture included many beautiful simulation movies that attracted a lot of interest and attention. Naturally, there were many questions from the audience that consisted of about fourteen keen researchers, so it took almost two hours for the colloquium to conclude.

Person of the week

The Astrophysical Journal, Volume 808, Issue 2, article id. 164, 26 pp. (2015).
This research is going to be introduced in RIKEN Research Highlight in the near future.

Matter Mixing in Core-collapse Supernova Ejecta: Large Density Perturbations in the Progenitor Star

Mao(**), Ono(**), Nagataki(*), Hashimoto, Ito(*), Matsumoto(*), Dainotti(**), Lee(*)
*: Current iTHES Members
**: Past iTHES Members

Abstract: Matter mixing is one important topic in the study of core-collapse supernova (CCSN) explosions. In this paper, we perform two-dimensional hydrodynamic simulations to reproduce the high velocity 56Ni clumps observed in SN 1987A. This is the first time that large density perturbation is proposed in the CCSN progenitor to generate Rayleigh--Taylor (RT) instability and make the effective matter mixing. In the case of a spherical explosion, RT instability is efficient at both C+O/He and He/H interfaces of the SN progenitor. Radial coherent structures shown in perturbation patterns are important for obtaining high velocity 56Ni clumps. We can also obtain matter mixing features and high velocity 56Ni clumps in some cases of aspherical explosion. We find that one of the most favorable models in our work has a combination of bipolar and equatorially asymmetric explosions in which at least 25% of density perturbation is introduced at different composition interfaces of the CCSN progenitor. These simulation results are comparable to the observational findings of SN 1987A.
Jirong Mao (1st Author, as shown in the picture on the left columun.)
Density Distribution of Our Best Numerical Simulation for SN1987A.
Mushroom-like Hydrodynamic Instabilities are growing with Jet-like Grobal
Asymmetry in the Ejecta Region of SN1987A.